Device for pushing a bar through a drawing die



Aug. 2, 1966 H. SCHNEIDER DEVICE FOR PUSHING A BAR THROUGH A DRAWING DIE Filed Dec. lO,

/nventon United States Patent O M' 7 Claims. (di. 72-284) The present invention relates to a device for pushing the front end portion of a bar through a drawing die of a draw bench.

During pushing of bars (profile, dat iron bars, or the like) into the drawing die of a `drawing bench by means of jaw-like pusher means driven -by appropriate drive means in horizontal direction, the end of the bar which projects beyond t-he front portion of the pusher means and which has to be driven through the drawing die can not be properly guided by the pusher means. Therefore, the free end portion of the bar is liable to bend or to buckle when the moment of resistance thereof does not surpass the buckling forces imparted thereto during driving of the front portion thereof into the drawing die. After the free end portion of the bar has been bent it is evidently impossible to push the same any longer through the drawing die. These difficulties arise especially if the bar has a cross section having a small moment of resistance in one plane, for instance with a flat iron bar.

It is an object of the present invention to overcome this disadvantage of known devices for pushing the free end portion of an elongated bar through a drawing die.

It is an additional object of the present invention to provide for a device for pushing the front end portion of a bar through a drawing die in which bending or buckling of the end portion of the bar during the pushing operation is positively prevented.

With these objects in view, the device according to the present invention for pushing the front end portion of a bar through a drawing die mainly comprises pusher means having a front end portion for gripping a bar with an end portion of the bar projecting beyond the front end of the pusher means and for pushing the bar through a drawing die, and a pair of auxiliary jaws slidably guided in the pusher means and projecting with portions thereof beyond the front end of the pusher means and slidingly engaging the end portion of a bar pushed by a pusher -means into the drawing die to prevent buckling of the end portion as it is pushed through the drawing die. The auxiliary jaws retract into the pusher means during pushing of the bar into the drawing die.

Preferably the device includes also resilient means carried by the pusher means and engaging the auxiliary jaws to resiliently resist retraction of the latter into the pusher means. The resilient force which resiliently resists retraction of the auxiliary jaws into the pusher means may be provided by one or a plurality of compression springs which during pushing of t-he front end portion of the bar through the drawing die will be compressed and which will, after the pushing action has been completed and the pusher means been retracted, restore the original position of the auxiliary jaws with respect to the pusher means so that the auxiliary jaws will again project with portions thereof beyond the front end of the pusher means to be ready for the next operation. The elastic force acting against the auxiliary jaws may also be provided by hydraulic or pneumatic means.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will he Patented August 2, 1966 best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. l is a longitudinal cross Section through the device according to the present invention and FIG. 1 shows also a 'bar held by the device and a drawing die; and

FIG. 2 is a front view of the device as shown in FIG. l.

Referring now to the drawings, it will be seen that the device according to the present invention for pushing the front end portion of a bar rz through a drawing die g mainly comprises pusher means which may include a pair of elongated main jaws b1 and b2, only partly illustrated in FIG. l, .and which have clamping faces engaging opposite sides of the bar a which may, for instance, be a flat iron bar as shown in FIG. 2. The elongated main jaws b1 and b2 are only partially illustrated in FIG. l and the pusher means includes in a known manner also means for pressing the clamping faces of the two main jaws b1 and b2 against the bar, and to move the pusher means in substantially horizontal direction so as to push the front end portion of the bar a extending beyond the front or right end, as viewed in FIG. l, into and through the drawing die g. Each of the main jaws b1 and b2 is formed in the right end portion, as viewed in FIG. l, with an elongated slot of substantially T-shaped cross section extending from the respective clamping face into the respective main jaw and a pair of auxiliary jaws c1 and c2 of likewise T-shaped cross sections are respectively guided in the aforementioned slots to project with end portions thereof beyond the front end of the pusher means. Each of the elongated main jaws b1 and b2 is formed rearwardly of the aforementioned slot thereof with a bore extending in longitudinal direction thereinto and having a closed rear end. Compression springs f1 and f2 are respectively located in the aforementioned bores abutting with one of the ends thereof against the closed rear end of the respective bore, while pins e1 and e2 guided with rear portions thereof in the respective bores abut with one of the ends thereof against the other ends of the aforementioned springs and with the other ends thereof against the rear ends of the auxiliary jaws c1 and c2, respectively. The springs f1 and f2 may be in the form of coil compression springs, as shown in FIG. l, or the springs may also be in the form of a plurality of oppositely curved spring washers arranged in abutting relationship in the respective bores.

The above described device will operate as follows:

At the beginning of operation the various components of the above-described device will be in a position relative to each other and to the bar a as well as to the drawing die g as shown in FIG. l. The main jaws b1 and b2 of the pusher means are pressed `against each other by means not shown in the drawing to properly clamp the bar a between the clamping faces thereof and the front end portion or right portion, as viewed in FIG. 1, of the bar a which projects `beyond the front end or right end of the main jaws is engaged at opposite faces thereof by the clamping faces of the auxiliary jaws c1 and c2, the rear portions of which are slidably guided in the slots of the main jaws and the front portions thereof project beyond the front end of the pusher means. As can be seen from FIG. 2, the clamping faces of the auxiliary jaws c1 and c2 are substantially flush with the clamping faces of the main jaws b1 and b2, but the clamping faces of the latter engage at least at rear portions thereof where they are not intersected by the aforementioned slots a much greater Varea of the bar a than is engaged by the clamping faces of the auxiliary jaws. When the pusher means is now pushed in horizontal direction forwardly towards the drawing die g the front end portion of the bar will be pushed into the opening formed by the drawing die and the front ends of the auxiliary jaws c1 and c2 will engage during further movement of the pusher means towards the right, as viewed in FIG. l, the front face of the fixed drawing die g so that the auxiliary jaws c1 and c2 will be retracted against the resilient forces of the springs f1 and f2 into the slots in the main jaws b1 and b2, whereby the guide faces d1 and d2 will properly guide the auxiliary jaws. Buckling of the front end portion of the bar a as it is pushed through the opening in the drawing die g will thereby be positively prevented. To facilitate sliding of the auxiliary jaws c1 and c2 with respect to the bar a, the faces of the auxiliary jaws which are directed towards each other may Ialso be set back for a very small distance with respect to the clamping faces of the main jaws, as shown in FIG. 2, but of course the clearance thus provided between the faces of the auxiliary jaws and the corresponding surfaces of the bar a has to be so small that the bar a is properly guided and prevented from buckling. After the front end portion of the bar a has been pushed through the drawing die g the clamping pressure on the main jaws is relieved and the pusher means are retracted whereupon the springs compressed during the pushing in operation will return the auxiliary jaws c1 and c2 again to the position shown in FIG. l. Stops may also be provided preventing the auxiliary jaws from moving completely out of the main jaws.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in -other types of devices for pushing the front end portions of bars through drawing dies, differing from the types described above.

While the invention has been illustrated and described as embodied in a device for pushing the front end portion of a bar through a drawing die, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features, that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A device for pushing the front end portion of a bar through a drawing die comprising, in combination, pusher means having a front end portion for gripping a bar -with an end portion of the rbar projecting `beyond said front end of said pusher means and for pushing the bar through a drawing die; and a pair of auxiliary jaws slidably guided in said pusher means and projecting with portions-thereof fbeyond said front end of said pusher means and adapted to slidingly engage the end' portion of a bar projecting beyond the front end of said pusher means to prevent buckling of said end portion of the bar as it is pushed through the drawing die, said a'uxiliary jaws retracting into said pusher means during pushing of the -bar into the drawing die.

2. A device as set forth in claim 1, wherein said pusher means includes a pair of elongated main jaws in which said auxiliary jaws are respectively slidably guided.

3. A device as set forth in claim 2, wherein said main jaws have clamping faces adapted to engage the bar over an area considerably greater than the area engaged by clamping faces of said auxiliary jaws.

4. A device as set forth in claim 1, and including resilient means carried .by said pusher means and engaging said auxiliary jaws to resiliently resist retraction of the latter into said pusher means.

5. A device as set forth in 4claim 4, wherein said 1resilient means are in the form of compression springs.

6. A device as set forth in claim 2, wherein each of said main jaws has a clamping face spaced from and facing the clamping face of the other main jaw and each vbeing formed in a front portion thereof with an elongated slot of T-shaped cross-section extending from the clamping face of the respective main jaw into the latter and wherein each of said auxiliary jaws has a T-shaped crosssection and being guided in the slot of the respective main jaw for movement in longitudinal direction.

7. A device as set forth in claim 6, wherein each of said main jaws is formed rearwardly of said slot with a longitudinally extending bore having a closed rear end, and including a coil compression spring in each bore engaging with one end thereof said closed rear end of said bore, and a rod guided in said bore and engaging with one end thereof the other end of said spring and with the other end thereof the respective auxiliary jaw.

References Cited by the Examiner UNITED STATES PATENTS 2,228,749 l/1941 Berkebil 72-284 2,732,932 1/1956 Strock 72-284 FOREIGN PATENTS 253,759 11/ 1948 Switzerland.

CHARLES W. LANHAM, Primary Examiner.

H. D. HOINKES, Assistant Examiner. 

1. A DEVICE FOR PUSHING THE FRONT END PORTION OF A BAR THROUGH A DRAWING DIE COMPRISING, IN COMBINATION, PUSHER MEANS HAVING A FRONT END PORTION FOR GRIPPING A BAR WITH AN END PORTION OF THE BAR PROJECTING BEYOND SAID FRONT END OF SAID PUSHER MEANS AND FOR PUSHING THE BAR THROUGH A DRAWING DIE; AND A PAIR OF AUXILIARY JAWS SLIDABLY GUIDED IN SAID PUSHER MEANS AND PROJECTING WITH PORTIONS THEREOF BEYOND SAID FRONT END OF SAID PUSHER MEANS AND ADAPTED TO SLIDINGLY ENGAGE THE END PORTION OF A BAR PROJECTING BEYOND THE FRONT END OF SAID PUSHER MEANS TO PREVENT BUCKLING OF SAID END PORTION OF THE BAR AS IT IS PUSHED THROUGH THE DRAWING DIE, SAID AUXILIARY JAWS RETRACTING INTO SAID PUSHER MEANS DURING PUSHING OF THE BAR INTO THE DRAWING DIE. 